Loudspeakers create sympathetic vibrations in neighboring items. This phenomenon is like the sympathetic vibrations induced in a piano string by a tuning fork. The sympathetic vibrations within a audio listening environment are often heard as buzzes that may either seem random or as regular beats in time with musical tones.
In a vehicle, such as an automobile, these buzzes are found in trim panels, door panels, instrument panels, and windows and the associated structures and mechanisms. As audio entertainment systems and communication systems become more powerful, the problem is exacerbated. Automotive engineers find that designing a buzz-free listening environment is quite a challenging endeavor. Conventional designs involve use of stiff structures with an abundance of fasteners and vibration dampening and cushioning materials.
Testing for buzzes has conventionally been carried out by using standard listening devices, such as the radio or tape or CD players. The automotive engineer simply turns on the radio, perhaps to a loud rock station, or the engineer puts on a tape of music with like characteristics. Any buzz readily identified is located and corrected. While this technique works to some extent for major buzzes, the less discernable buzzes are usually masked by tones in the music and voice of regular programming, tapes and recordings. And while small, frequency sensitive buzzes are difficult to locate, they tend to cumulate to bring about a net effect that detracts from the system, both to a listeners consciousness and subconsciousness.
The problem of the sympathetic buzz is exacerbated with light and less expensive (with less materials) automobile as are found in great abundance in today's automotive market.